# Equality of quantities: if 5 [bird] =8[legs] can i conclude At each 5 bird i would have 8 legs?

#### Ryan$##### Junior Member Hi guys; so sorry for posting loke this question but please im not that much smart turly and im not afraid of this; so i make double work for understanding anything.. My question is: if theres like this: 5 [bird] =8[legs] so can i conclude from this .. At each 5 bird i would have 8 legs? In other words here i can conclude from "equality" that 5:8 is also work for manipulation of how many legs within 10 cats..! What I'm trying to say we can conclude from the "=" between birds and legs that 5:8 is also right for manipulation...I mean however it's "=" in equality equation; we also can conclude ":" 5:8 from the same equation(from bird=legs).....am i right? #### pka ##### Elite Member Hi guys; so sorry for posting loke this question but please im not that much smart turly and im not afraid of this; so i make double work for understanding anything.. My question is: if theres like this: 5 [bird] =8[legs] so can i conclude from this .. At each 5 bird i would have 8 legs? In other words here i can conclude from "equality" that 5:8 is also work for manipulation of how many legs within 10 cats..! What I'm trying to say we can conclude from the "=" between birds and legs that 5:8 is also right for manipulation...I mean however it's "=" in equality equation; we also can conclude ":" 5:8 from the same equation(from bird=legs).....am i right? Dear Ryan$, you really need to enroll in a course that may go be many different names but it is philosophical logic. I think that I remember that you are in a area with several higher education units each of which has such a course.
At the very least get yourself a copy of Copi's Symbolic Logic, See Here If I were you I would buy a used copy in good condition.
You can read the material on Definite Descriptives. Bertrand Russell contributed a great deal to this the whole area of mathematical logic, especially the concepts of equality & identity.

#### Dr.Peterson

##### Elite Member
The statement "5[bird] = 8[legs]" means only what you intend to mean when you write it. Any symbols can be misused (just as one can put words together to make nonsense), and many can be used in more than one way.

What do YOU mean when you write that? I have never seen something like that written in a mathematical context.

##### Junior Member
how from equality "=" we move implicitly to ":"

#### Ryan\$

##### Junior Member
Is one of the birds a double amputee?

no ! but I mean that how from equality we can conclude ":" a relation between birds and legs

#### Dr.Peterson

##### Elite Member
I mean with "writing that"; from this statement=5[bird] = 8[legs] we conclude that at every 5bird there's 8legs; so it's equal to say 5:8 .. And then if we need 10birds we would have 16legs .. So first the equation was "=" and we concluded something that's related to ":" so how is that logically?!
So you are using "[bird]" and "[legs]" like units (1 foot = 12 inches), and not as variables (number of birds, number of legs), which would have a very different meaning.

The fact is, we don't write "5 birds = 8 legs", because they are not the same thing. We would say in words, "for every 5 birds there are 8 legs" (if, of course, we had very odd birds). That would make it clear what we mean, which is a ratio. So your question is about something that doesn't exist.